The entire disclosure of Japanese Application No. JP-11-143656 filed on May 24, 1999 including specification, claims, drawing and summary are incorporated herein be reference in its entirety.
The present invention relates to a navigation system arranged to display an enlarged view of a branch-point image by using image data when the vehicle is within a predetermined distance from a branch point such as an intersection on a suggested route. The present invention also relates to a storage medium having a program for executing the above-described display processing.
A typical navigation system for vehicles searches, upon entry of a destination and a transit point, for a route to the destination and guides the vehicle to the destination. There is known a navigation system arranged such that when the vehicle is within a predetermined distance from an intersection on a suggested route at which the driver should turn, the navigation system displays an enlarged view of the intersection prepared from road node data or displays image data concerning the intersection that has been stored in advance. FIG. 9 shows an enlarged view of an intersection and an enlarged view of a branch point, which are displayed by such a conventional navigation system. Thus, an ordinary map prepared from road node data is displayed on the left-hand part of a two-part split screen, and an enlarged view of a branch point drawn by using image data is displayed on the right-hand part of the two-part split screen. On the map prepared from the node data on the left-hand part, a mark A indicating the present position of the vehicle is shown. On the right-hand part displaying the image data, only a direction in which the vehicle should advance is shown, but the present position of the vehicle is not displayed.
An enlarged view of an intersection prepared from road node data has coordinates as position information concerning nodes. Therefore, a mark indicating the present position of the vehicle can be displayed so as to move according to the distance between the vehicle and the intersection. In an enlarged view of an intersection drawn by using image data, however, because the image data has no coordinates, a present-position mark cannot be displayed nor moved according to the distance between the vehicle and the intersection. Therefore, with an enlarged view of an intersection displayed by using image data, the user cannot ascertain the present position of the vehicle at the intersection and may mistakenly turn at an intersection adjacent to the suggested intersection or pass the intersection at which he or she should turn.
In view of the above-described problems, an object of the present invention is to provide a navigation system of the type wherein an enlarged view of a branch point such as an intersection is displayed by using image data, which is designed so that a present-position mark can be displayed superimposed on the image data and the present-position mark thus displayed can be moved according to the distance between the present position and the branch point.
To attain the above-described object, the present invention provides a navigation system including a present-position detecting unit for detecting the present position of a vehicle and an input unit for entering a destination and information necessary for a route search. An information storage unit stores data necessary for a route search. The data includes branch-point image data having coordinates added thereto according to the distance from a branch point, such as an intersection, and road data. A display unit displays route guidance information. A route search unit searches for a route to the destination on the basis of the information entered by the input unit and the data stored in the information storage unit. A control unit reads the branch-point image data when the vehicle is within a predetermined distance from a branch point on a route found by the route search unit and outputs the branch-point image data to the display unit so that a present-position mark is superimposed on the branch-point image data on the basis of the coordinates of the present position detected by the present-position detecting unit and the coordinates added to the branch-point image data.
The present-position mark may be displayed so as to move according to the distance from the vehicle to the branch point.
Preferably, the image data has a flag indicating whether or not the image data has coordinates added thereto according to the distance from a branch point such as an intersection.
Preferably, the image data includes data concerning the size thereof when it is expanded, and has a coordinate offset from a specific coordinate point to a display reference point.
In addition, the present invention provides a storage medium having a program including the step of detecting a present position and the step of storing data necessary for route guidance. The data includes branch-point image data having coordinates added thereto according to the distance from a branch point such as an intersection. The program further includes the step of searching for a route and displaying route guidance information, and the step of comparing the coordinates of the detected present position with the coordinates added to the branch-point image data when the present position is within a predetermined distance from a branch point on a route found by the searching step, and displaying a present-position mark superimposed on the branch-point image data.
In addition, the present invention provides a storage medium containing branch-point image data having coordinates added thereto according to the distance from a branch point such as an intersection and further having data concerning the size of the image data when it is expanded and a coordinate offset from a specific coordinate point to a display reference point.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.
The invention accordingly comprises the features of construction, combinations of elements, and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims.